Herbal flea collar not working? What to use instead

Herbal flea collars are one of those products that sound reassuring but have very little evidence behind them — so it's not surprising the flea population hasn't budged after months of wearing one. Before I point you toward something that will actually work, there's a critical safety note specific to cats: permethrin and several other insecticides that are fine for dogs are toxic to cats and can be fatal, so it's essential to use only products labelled specifically for cats. To make sure I recommend the right thing: how old is your cat and roughly how much do they weigh, is this an active infestation or are you now moving into prevention, and have you treated your home — carpets, furniture, bedding — as well as the cat?

Right, that all makes sense — and the fact you're still getting bitten yourself tells us there are flea eggs and larvae in your carpets and soft furnishings, which is where roughly 95% of the flea population actually lives. The collar was never going to touch that. For a 10-year-old Persian at 4.5kg, can I ask one more thing: does she have any known health conditions or is she on any regular medication? Older cats can sometimes have sensitivities, and I want to make sure the product I suggest is the right fit.

Great — that makes this straightforward. I'd recommend Advantage 80 Spot-On for cats over 4kg. It's a pipette you apply to the back of the neck once a month, it kills adult fleas on the cat within 24 hours, and it also kills flea larvae in the immediate environment through contact. It contains imidacloprid, which is a well-established, cat-safe insecticide — no permethrin risk. For a 4.5kg cat, the Advantage 80 dose is exactly right. You'll find it on Amazon UK in packs of 4 pipettes, which is a sensible amount to get you through the initial push and into a proper prevention routine. The reason I'm suggesting Advantage over a combined product like Broadline at this stage is simplicity — she has no worm concerns flagged, and Advantage is very well tolerated even in older cats. One important thing alongside this: you need to treat your home at the same time, or you'll keep reinfesting her. Use a household flea spray containing IGR — insect growth regulator — such as Indorex or RIP Fleas. Spray all carpets, skirting boards, under furniture, and soft furnishings, then don't vacuum for at least two days.

Monthly, year-round — and I know that sounds like a lot if you've not done it before, but it's genuinely the only reliable way to stop this happening again. Fleas don't disappear in winter in centrally heated homes; the lifecycle just keeps going. If you treat the cat once and stop, you'll likely be back in the same situation within a couple of months. Once you've cleared this infestation with Advantage and the home spray, staying on a monthly Advantage schedule means you'll catch any new fleas before they get a foothold. Think of it as maintenance rather than treatment at that point.

Good plan. To recap: Advantage 80 on your cat today, Indorex or RIP Fleas sprayed throughout the home on the same day if possible, leave the spray to work for at least 48 hours before vacuuming, then Advantage once a month going forward. Most people see a significant drop in live fleas on the cat within a day or two, but it can take 6–8 weeks for the full infestation cycle in the home to break — so don't be disheartened if you still see the odd flea after week one. You're doing the right things. Good luck to you and your Persian.